// Copyright (c) 2013, Jose L. Hidalgo Valiño <pplux@pplux.com>
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// 
//   * Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
#ifndef __SLB3_EXTRA_STACKGUARD__
#define __SLB3_EXTRA_STACKGUARD__

#include "../config.h" 
#include <cassert>

namespace SLB3  {
namespace extra {
  
  class StackGuard {  
  public:
    StackGuard(lua_State *L, int stack_balance = 0)
        : stack_(L)
        , stack_at_end_(lua_gettop(L)+stack_balance) {}

    ~StackGuard() {
      assert(lua_gettop(stack_) == stack_at_end_ && "Invalid stack balance");
    } 
  private:
    lua_State * const stack_;
    int const stack_at_end_ ;
    StackGuard(const StackGuard&);
    StackGuard& operator=(const StackGuard&);
  };

}} /* SLB3::extra */

#endif
